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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d7ad28f11018b3c2d061c641760a793d6eb4a580984b8eb35a4b6f241bb2c42' 
  AND token = '2AESN5CKFHwlZ6ZNTeTJryjkh6UUgJfrh1/FQk7/HSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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