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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '851f0b1f47360bf10326944347865d8c526e5bc768e419ac5402eb61df0f307d' 
  AND token = 'DjOzSTyjeW1dFt0sfvM7E/xwHMSH0/b9yfBPiXfOgig=' 
  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"
    }
  }
}