SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '103e484f780d92d572fb88bdeca451d35aaacf0ffc98665013ecf3ecce1d2e48' 
  AND token = 'CC2YaNoscH91CXFVxTWKc2wpyVTKSngpGfB1qSMfycI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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