SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f5037e2a46c0a0a1412b116043dc86ca47bbe4b133a2463b1a022a5beaf6fd3' 
  AND token = 'mZ5TFi9JQS5UGQ4IGbb9Yi/6AxPlIqBBhuV7+jCcGnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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