SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3071b68f41a00cfef2ebd6c9a245f904af5970a9e44d274ed3d4f714df295ad7' 
  AND token = 'pnUgkMtrh//bo9lxfRnkfpNco2Ntxesaf0PKZnGNa30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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