SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ea57d50af48e7517f25c740aa00516c627a65c9ae2c13d64f7b6816acda2474' 
  AND token = 'W3vq9eRRESbHKr7tg8j/u0TevZZviYRPgIGlJnBoT4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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