SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '650d121976597f25f5d168f494af27094f1902e6954ee12843942a3f5e924e02' 
  AND token = 'QGiRPHN4hiUhIf/VO28FVpOlAioAfzprm1fcfHH2PnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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