SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '976c863b359926e7958779273179f6ccebd1a1407a2586bc5c3d250565340555' 
  AND token = 'EYQ0P9sCwQZHEXubENn04bMLv5dMH6gHcxpdpAONK0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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