SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '529935450f1729d9ccb27d0861d22869db442f79548b91d706a110e92166df60' 
  AND token = 'TXyTvlRDzDxdM88Qj8oTAUIFTW9svxsLbeSNSUtDTkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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