SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '724b1dacfd9ecc980909b91402a3304b548b73992e902cd2ee4104cd80c23cbc' 
  AND token = 'nEWXaG84+rtkRfaTHkluVeBkQpHIW5raJYZolhJ4KM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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