SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b48b012682dbb83b3da87032b409643c0f721fdd1932bcd0daa78af28234184c' 
  AND token = '1g9ftAKKPrcGpnozyrD983+MLgnFGOkus7WKM0U2AwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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