SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4294e02d7a3a593d18f6a35151b0666326b0cd059cb1b3b1feb505dc49abf9fb' 
  AND token = 'P3FQ4Opq+FfWAfJWqEU9qg6ZKvZMoWV2VrNJMzToLBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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