SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16936fa53ada26233dacacdf878914d3c53bfb4b701566d25c09b000ba98f1f9' 
  AND token = '215GzYZxO7j2RmxwhuBYTndYEfTAJ5qWHEmBBTLNVVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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