SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4470fe4434c87feaf8753d949207e3a013594d984160dc1235b2b82bbcea8b6' 
  AND token = 'l0WixV5aVPsjc3FcpQm+JR5z62jT6tVOZeqPVVGYE2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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