SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12d1624841a8e4f42d271032b40969ad58cb447dba9692ae60f0d2f43186f3d9' 
  AND token = 'fPmGjeSnuMqKRKERvSan3uR1O/fY5ecOOOzQdpia5yI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}