SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6a5b933ba1b9d766e70eff206bdd3c156e78d8cd303d4d71a98985b548dcd43' 
  AND token = 'sTjsrcUuatESuZLNDdop2vC4NDN7RzSbVIHz84EXJVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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