SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bd61a516fde36fcde201def5213ad2b5a89a953296b717a809aac14c3f1effc' 
  AND token = '+Pay8b3einWSPNLKoctSOX6B2jmKyv8VqAQ09eGCOck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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