SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2694e6c32ac316c1d501f22381e8497e561d2cca8dfcaed3d79ed5f9c2e88375' 
  AND token = '4alFTQ6R3nzHlll8cBRgUEgICizSDVdCyjLYinghuio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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