SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ebd9ef3158d7ba215a18965a8422c7fdacb30038eeb216cb3117e5b82e98bf4' 
  AND token = 'OdwmYP6HadFLh+rqiZsiJwc80rErlhOjOruKiyA0Baw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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