SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b17f43a357a8314075029518360ced4c95956ecf23d15ce123a7fa4f593639af' 
  AND token = 'KrSgy6zSPPyErgfrjvvT6OeGFYjzao/bLZJ+BO9nTWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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