SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28925f5c50ec340e9c8644e65aba65d4995c135e94cf80df0d35ee3b3289b880' 
  AND token = 'n6c+Juo6h9+1aIjl9JPADxkoOWO6KwmUtgiGlf51XjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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