SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '253cd20f3473771c1e65aa43a4e74b8ea0dee6dadee8cd4f10c1eac1daf6e421' 
  AND token = 'GK3Bry8ZgdydNLmVR2iaPvU20c47A1O28whOjSj+aq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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