SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50aac1bd8beacb4f923f2d0dbf369cdead64a04ae8823981cdc7912650935157' 
  AND token = 'sSp4G53hLjofMhYcK6qtXr+xFknAxs7aVREf+lXn0tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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