SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91940b4f9738431d48f00cac521dbd08da9a5781677b1283d083886e4430c273' 
  AND token = 'gFOQbvee5KBqt+1cXEhJGAKZNL3qBX7j+q0aiQ9nKDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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