SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52915c7fd99fb0f1592657e8300805201d9d1dad3269c8419704f0be65f5b0bd' 
  AND token = 'ICZqaWcG9MtcG7HP+Dw0bG3fnsKvfmrgeEoKUDioB7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}