SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f9db3a399c6208284377451a7dc69dbb2e5e4470e41e0608482785bb2b19e61' 
  AND token = 'sFxs/jZ8XMTPgRBHSBvzrd3Da2raJLgk9/LGxq+GGTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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