SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbe103e44e23b36498ca9535504070f7e83bc7072fd3193bccc1b89dfdfbddb5' 
  AND token = 'kPHpsQWZcCda3B93VWrvpY1IfPpU3s+rvQ7qUz2Nsp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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