SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '275047740d2417e96356426f3c32e6d692fec79305113eed03e618b764686954' 
  AND token = 'biiUtrbyyXIiafwyaQVPbK22DWZYd5EaeE1zAEW8K24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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