SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '328ea251bc61a9a3655c5ea1c979b24ed62dea29ce8e33668fe1c0be05905d9b' 
  AND token = 'kNRkLn9eq9G/6n3WyFnqVlSQNJBoMHD+E2vh9riy5Lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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