SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bce7d3dd812926bf42c295253ecfee42b149346539c861c469d2187b7b7e72f' 
  AND token = 'R06sxofrtPerpphoXq9Y9S7+343viGhoKzc68qsOuQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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