SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4468dfc2dd943e0fb34d8f4562459bcd58b1785495fe66961c668659be81e7f7' 
  AND token = 'LR6KpAAKXn0d6OFk6mAccQKmqsadoeJo2azedPQvyig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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