SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f25a36796692ed75211e2c4a8e7e384d3faad02289791990b3506de884a5956' 
  AND token = '9pTvz+5wmRwnEoIiwWC350B3BLwiQpY56X5Nd5CFCGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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