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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67158d27f06caec7b06627a7ca0a00f2760ff6b11b4ec7cc3bca9a5afdaa23e8' 
  AND token = 'dKa3LW9MULRrTHzdT/XJ5/KykS02opc71kdiA5ThsGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}