SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bea3bdf4e328d17a7e857093aee49d3c56f40d2f22fb4766e7072f4594b274b' 
  AND token = 'S6VtwyDHceVi0p6C1hRLDU0ou7mQwD+BHNf6Z/AdMOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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