SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3603af09216691a76e3df2ea0fbecbcf59ecc1c8cb8d678acc112fd05cf5e97' 
  AND token = 'nQi4AicRDfNKoa+gfn9dQ8xjxHCgrSFet6rRidadbxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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