SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2a65004d5454e4c692fffb571291695c39c63f4df08d96903cdc8ab96038c81' 
  AND token = 'l6cexk+2CRusqPGfAtu+DjdaLxXgdsVim2YkQKhgNkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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