SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'def999ddcdcedabd195a633bc0a9625d7faadc6f43937550908ad234bfdd0538' 
  AND token = 'g9kRJbawFXbXm2kZ48pwp5NUDxE+RzaTbIcduZQvra4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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