SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4290f9b2b0c1cc6f2212e10b165b6d0bad9617265d20efeed76b645080acd5d6' 
  AND token = 'r8c0y2rfsBdx1pNiETTrwl3ovXRTRexdUu1pYgTSrjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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