SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '758edd616ddab581e77215bea1a7eab49199984b7972f17f0851c13edc0d16a2' 
  AND token = 'x+V52Ui4AraY89rS2SSZB5rzTG8qCbxevcuNSWNZ4GY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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