SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a71ff193f9386b61f4377e0d36a13cab336bf473583a894a7bb6d550fb8a58e2' 
  AND token = 'bfPwPRLC3KPDVQ8mttcQKBxP4IpwDLGVLqzqRW7wB+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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