SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6bedb1de421571857508c0d7413bff4a02382dff3154db796b0d170c2b1c915' 
  AND token = 'WjQ7Wbo4DX729CRy1rORkGj7CskuA38IrihHNOiftTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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