SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6858ea9cf41f78cc9bffd41ca47dd57d87cd7a877cafcf5e049a39a39974e343' 
  AND token = 'GR8eYbV+prMz2RFXHoRCE5QU+wxWPBdvNSFOI5C+QjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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