SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b749ff499b81c43d007c5778dbec6752a23cd43cc3e31dd6bea5ba7db05b0a34' 
  AND token = 'SCMZ36PCPioe3u+QrO3Z2jq7t2QbKpiPTOhk/vsyGRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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