SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b12fb81a7d954cd1f044024afb185598068f8628201c6cc4d31c3e28d095fcbe' 
  AND token = '2bZwvT1g99PUNKc9yeV8/D6rQVqqIe0evdsXaLHClnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

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