SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b50aed30dbc8b08286c07e1a3e64f68ee7170b91c0a6a2819588b955d48e8d64' 
  AND token = 'Eckuuko4jjdTajYRbK0bW7DMnMsKSPRpLqzeBqPEoy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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