SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40c8bc9cd06a8b90086a0bf081ab85fb3f90d97b7303f334a552a75ac0f6c4be' 
  AND token = 'aTr3TiWShbcAK/Cb2OI9eXWkczhXUXGzpTwza0eHbsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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