SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c246803a07f2b05fa5ac37e47421fff73f81ca88a79bdb464b99667fc016081a' 
  AND token = '2oxjyD/JNgwOxjZ/ctCo96Pz8xwqCjJNVKIh4PtF4V4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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