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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d435df9ab00af302d2d469544e07ab3df21d80ce768e75dc7e73beb000b5e54' 
  AND token = 'sRXMloMvz+ugsuK4/nUP31AsdXVo8X7Kj8G+8SqgRrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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