SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92b9fd9c930ac71aeffb3f3d108461f7d8fe6732121ce0cad023da1816eecce2' 
  AND token = 'pQK9z6AHIi46zsJM8eNFgaL1DQ29jajyQr8EXopj6xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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