SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9f9c19c65b2b4f52bedfa8c5f34947fe8724a97c2c37134d1d04171fa62d1480' 
  AND token = '/OiTxzz9zSZmfBe00JJgpbTGmTl4+gLSUCmZZP62k/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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