SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81dedff82069d9a422bce53bd1cf5b0ea1950197171c56b04141a400abd57e01' 
  AND token = 'uR/JolTvfpmit/39RFBqsGqUWspFEl85Q64h5hp0r0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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