SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '238a3e3555fd2e7d62ec1962982de4b14f30912ac7fd10fb12c9200539edfa56' 
  AND token = 'KhUVg3WeW1Ls67sOSNUYTrEbHvF2MPBExCD7/tcrMgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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