SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c6dc8f3eb2fd64951f27397403526eb67d5ffafabd0f8f447541bf3e3fd0cc8' 
  AND token = 'DOexwdvI1nChSPgwzAWPPkW5ow1t+KMQHoYQFq5UtHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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