SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb921ba8d3562afff73ad712f2cd331c60349f9f8d646bd1e1dfbd3839f2029f' 
  AND token = 'hmv/X42PfqnucTK46RLJeqJBKmhlt3YAE+4KPhmaoSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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