SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94f90a8864cccf028d3940002a3979d18de5bf8dddf3d78544e0a9d13c4b6ba6' 
  AND token = '4k+gjXfsoByhfhPz6dlcOkTcJVDkRBoGJDmgwFcjU9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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