SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a6cbefa3e1fc7ed39df41731608b84d907c94bf742af60a57ad29fd404affb8' 
  AND token = 'YqdxTgFlNixClsf60aJWXQ9X1NCZGKzvhKuXP3z/Q8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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