SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27c457f552dcd1ce8afa59e44eff673d254f505684f20e0cc9a95bdf91a5b4cf' 
  AND token = 'uI6/3pQ3KEt0tOQX/WQZgBZcUE1+cvXqaQKrZt2lCag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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