SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36fa360d9858649aae17967d53903df609ba7f162f987a2d6832a5faf307fc7f' 
  AND token = 'zKOzffgEzG4wP8cXVSwH59muflv4vqkcw/uWaDNPJFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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