SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c70adc1468b439fc97aec6bb3494faa2830eddb05b48bf946df74e09f4371a75' 
  AND token = 'eXWPpJYbQ1zjBVsrv73lou51kRD040afYqMM/P5JvEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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