SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '491c1065954ca315e72a6b89e2cb979a38258ee0e5fa5baeff7343606701aa2a' 
  AND token = 'P3Y2ouB/baGZM1DzHtlKA5f/ZYjnrEBswW0nKgDvuUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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