SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90bf7234803df2ca118f8eeb5a38f4c7caa241073db927f6fbe0d7f05be59e7a' 
  AND token = '3lw++KGdu5+qzvt6K2krfEy3mhkLjNA7O1t6zM/IJ9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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