SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79c0e22488610990d0a0960a1da9f6be7f691d289d68ada553b4ac892ab5ce50' 
  AND token = 'b+nEYXmbZTYAAtx3JMTOLjRoKRE6vP2RxaS9uoOsYzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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