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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dbd52c55f40f93f204d498fdf6a4c0b2eb42f164a8803572d6fe306610c0305' 
  AND token = 'NVBENl3qzKj4AwXWEaWGAEOe99EA2/91DqYuNWorS8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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