SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b975e91de4e2ceecfaa7f480ec748179c81ab2820a69c91bbe9c600a602d1786' 
  AND token = 'f5WDxndBsTKO6KHNwLzshhkkaF4Kscyd8Yb8v0/upXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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