SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90909c61bde0617a0595014cede0d54b00dcb13a04c66586b762a376797feedb' 
  AND token = '4gyi+5j6BvoEBoDHhP11gZgWxKZ3AeP3BLtN+KZVEKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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