SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bdc3aefed745a721cdcbe2d7985529694f5d6df774f44616c7f9a74d3d3b817' 
  AND token = 'kyly0OjiG1endtI/vptu+mOC99DKJkgfXVTZ8x2Jvj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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